It is known to equip a bearing ring with a glass fiber element to allow the measurement of different physical parameters. By doing so, a survey of the parameters becomes possible by using the fiber Bragg grating (FBG) method. By this method temperatures as well as strains of the machine arrangement can be monitored.
For doing so it is necessary to connect a glass fiber with the component. For surveying temperatures it is essential that a thermal coupling between the glass fiber and the machine arrangement is established. For monitoring strains it is necessary to mechanically connect firmly the glass fiber with the component to be monitored.
Specifically in the latter case problems arise because the glass fiber is normally equipped with a plurality of coaxially arranged cover layers. A typical construction employs a cladding arranged around the glass fiber (core) itself; the cladding is coated by a coating layer. Then, strengthening fibers (made e.g. from aramid) are arranged at the outer circumference of the coating. Finally the strengthening fibers are cased by a hollow cylindrical cable jacket.
When a glass fiber element of this type is connected with the component, a certain elasticity is immanent between the glass core and the component. Thus, specifically the measurement of strains is problematic due to the elasticity. This is specifically a problem when the component is not even or flat but if it has a spherical shape. This is typical in the case of a bearing ring, specifically of a roller bearing.
Another problem is arising when the bearing ring has only small dimensions. In this case machining grooves for embedding of the glass fiber in the bearing ring often takes away much steel and thus affects a significant reduction in the bearing stiffness and strength. Small bearing rings with respective grooves may damage easily and therefore sustain short service life.
Also, a high temperature bonding of glass fibers for carrying out the fiber Bragg grating method is always challenging. Traditional polymer glue does not meet with the requirements which have to be demanded for proper measurement of temperatures.
Finally, the installation and sustainability of bearings for installation and after installation is also often a problem.
There have been no pre-known designs which solve the mentioned problems. Connections methods have been known for small bearings but the connection of the glass fiber to the bearing ring protects only from oil and grease rather than provide a robust integration and high temperature applications.